It is hardly surprising that there should be a great deal of concern that a convicted sex offender was allowed to drive disabled children to school in the Bradford district. The people who raised the alarm were right to do so.

The problem appears to have arisen because of well-publicised staffing difficulties at West Yorkshire Transport Service, which has not had enough drivers to man the services carrying disabled people to day centres. As a result it was forced to sub-contract some of its work to a Keighley taxi firm, Bronte Taxis.

The owner of that company says he was aware that Matthew Wilde had changed his name but had no idea that he had a conviction for a sex offence for which he had served an 18-month prison sentence. He was understandably happy to accept Mr Wilde's offer to drive the children to school unpaid, saying he thought it was a goodwill gesture.

Mr Wilde says that no-one was at risk, and it is true that on the journeys the children were accompanied by an escort who had had clearance from the Criminal Records Bureau. It appears that no harm has been done.

However, this case highlights a potential weakness in the system used when the service is under pressure due to staff shortages. Bradford Council and Metro need to make sure the systems used both by themselves and the companies to which they sub-contract are watertight.

Meanwhile, those working in the service need to continue to be prepared to speak out if they have any concerns at all.